C++之重写运算符练习

 1 #include<iostream>
 2 #include<string>
 3 using namespace std;
 4 
 5 class MyString{
 6 private:
 7     char* cp;
 8 public:
 9     MyString(char*);
10     ~MyString();
11     MyString(MyString&ms);
12     MyString& operator +(MyString&);
13     MyString&operator=(MyString&);
14     MyString&operator+=(MyString&);
15     char operator[](int i);
16     char* getP();
17 
18 };
19 MyString::MyString(char*cp=NULL):cp(cp){
20 }
21 MyString::~MyString(){}
22 MyString::MyString(MyString&ms){//深复制
23     int len = strlen(ms.cp);//先确定原来字符串长度
24     char*tempcp = new char[len+1];//开辟足够的空间
25     strcpy(tempcp,ms.cp);//复制相同的内容
26     cp = tempcp;//初始化对象的指针
27 }
28 
29 MyString& MyString:: operator +(MyString&ms){
30     int len = strlen(cp) + strlen(ms.cp);
31     char *tempcp = new char[len+1];
32     strcpy(tempcp,cp);
33     strcat(tempcp,ms.cp);
34     
35     return *(new MyString(tempcp));//不改变两边对象的内容，返回一个新的对象
36 }
37 MyString&MyString::operator=(MyString&ms){
38     if (cp == NULL || strlen(cp) < strlen(ms.cp)){
39         if (cp){
40             delete[] cp;//释放原来的小空间
41         }
42         cp = new char[(strlen(ms.cp) + 1)];//开辟足够的空间
43     }
44     cp=strcpy(cp, ms.cp);//复制内容
45     return *this;
46 }
47 MyString& MyString::operator+=(MyString&ms){
48 
49     char*tempcp = cp;//暂存cp,因为要重新开辟空间//如果直接使strcat空间不够会出错
50     cp = new char[strlen(cp)+strlen(ms.cp)+1];
51     strcpy(cp,tempcp);
52     strcat(cp,ms.cp);
53     
54     return *this;
55 }
56 char MyString::operator[](int i){
57     return cp[i];
58 }
59 char*MyString::getP(){//用于主函数中查看对象内容
60     return cp;
61 }
62 int main(){
63     MyString ms1("hello"),ms2("world");
64     cout << "+result:" << (ms1 + ms2).getP() << endl;
65     ms1 += ms2;
66     cout << "+=result:" << ms1.getP() << endl;
67     ms1 = ms2;
68     cout << "=result:" << ms1.getP() << endl;
69     cout << "[]result:" << ms1[0] << endl;
70 
71 }

 1 #include<iostream>
 2 
 3 using namespace std;
 4 
 5 class Point{
 6 public:
 7     Point& operator ++();
 8     Point operator ++(int);
 9     Point&operator --();
10     Point operator --(int);
11     Point(){ _x = _y = 0; }
12     int x(){ return _x; }
13     int y(){ return _y; }
14 private:
15     int _x, _y;
16 };
17 Point& Point::operator ++(){
18     _x++;
19     _y++;
20     return *this;
21 }
22 Point Point::operator ++(int){
23     Point temp = *this;
24     ++*this;
25     return temp;
26 }
27 
28 Point& Point::operator --(){
29     _x--;
30     _y--;
31     return *this;
32 }
33 Point Point::operator --(int){
34     Point temp = *this;
35     --*this;
36     return temp;
37 }
38 
39 void main(){
40     Point A;
41     cout << "A的值为" << A.x() << "," << A.y() << endl;
42     A++;
43     cout << "A的值为" << A.x() << "," << A.y() << endl;
44     ++A;
45     cout << "A的值为" << A.x() << "," << A.y() << endl;
46     A--;
47     cout << "A的值为" << A.x() << "," << A.y() << endl;
48     --A;
49     cout << "A的值为" << A.x() << "," << A.y() << endl;
50     
51 
52 }

//使用全局函数重载

 1 #include<iostream>
 2 using namespace std;
 3 
 4 class Point{
 5 private:
 6     int x;
 7     int y;
 8 public:
 9     Point(int x, int y):x(x),y(y){}
10     friend Point& operator+(Point&one,Point& two);
11     int getX(){ return x; }
12     int getY(){ return y; }
13 };
14 
15 Point& operator+(Point&one, Point& two){
16     int x = one.x + two.x;
17     int y = one.y + two.y;
18     return *new Point(x,y);
19 }
20 
21 int main(){
22     Point p1(1,1),p2(2,2);
23     Point& result = p1 + p2;
24     cout << result.getX() << ":" << result.getY();
25     return 0;
26 }